Apparatus for measuring the pressure-flow characteristics of greases



Oct. 24, 1950 H G SMITH 2,526,832

APPARATUS FOR MEASURING THE PRESSURE-FLOW CHARACTERISTICS OF GREASES Filed Jan. 30, 1945 J CQ' .7

I I k ll. I 15 O I 27 11 l I 7 *HERS GJKEL 6. SMITH Patented Oct. 24, 1950 APPARATUS FOR; MEASURING .THE PRES-v.

SURE;- FLOW "CHARAG-TERI S TI S 0F 1 GREASES Herschel G. Smith, Wallingfo'rd, P'a.-,- assignorto" Gulf Oil C orporation, Pittsburgh; Pa}, poration of- Pennsylvania a cor- Applicatien january53b, 1946, seri lno. 644,369.

- This invention relates to an apparatus for nieasuring the pressure-flow characteristics of greases such :aslubricating greases as well assemifluid lubricating oils", Y

There are many known devices forjmeasuring viscosit or flow characteristics of greases, such as. lubricant greases, but many are not veryaccurate. and other are complicated and cumbersome to operate. In the testing of lubricating oils there is an apparatus commonly used which is quite accurate and easy to operate, This device is known as the Saybblt-Furol viscosi'meter and an adaptation of this instrumenthto thetesting of greases is desirable because of economy, accuracy andeaseof operation.

It istherefore an object of this invention to provide a new and improved apparatus for determining the pressure-flow characteristics of greases,

It isa further object of this invention to provide an apparatus for determining the pressureflow characteristics of greases utilizing a Saybolt- Furol viscosimeter. I

These and other objects of the present inventionare attained b an apparatus, one embodiment of which is illustrated in the drawings, which comprises generally a fiuidebath of I controlled temperature surrounding a'tube adapted to containa grease sample having a nozzle of a fine bore atits lower end. Superimposed over the sample tube .and detachable therefrom is a cylinder of larger diameter than the sample tube and adapted to. contain an additional amount Of the material to be tested. It is fitted with a piston having an upwardly extending piston rod. In operation a weight is placed onthe top of the rod of the piston causing pressure on the whole sample of the -material in both cylinder and tube and forcing the material through the nozzle. A balance placed under the nozzle catches the material as it falls through the nozzle, and from the time it takes a predetermined weight of the material to pass through the nozzle, pressure-flow characteristics may be determined.

'I'his apparatus is intended to determine the. pressure-flow characteristics of, a grease through the orifice of a Saybolt-Furol viscosimeter under conditions of definite temperature and pressure:

in -:the cylinder which need not be subjected to temperaturecontrol. The pressureis in turn'ap- The pressure is sup-- 1 4 Claimsr (Cl. 73-64) pliedito the smaller volume of grease. in the tube which is-at a controlled temperature.

One form' of the apparatus of this invention is illustrated in the accompanying drawings in which:

Fig. '1 is a side view partly in section of the entire apparatus and,

Fig. 2 is an enlarged sectional View of the upper pressure cylinder shown in Fig. 1.

With reference to Figul there is shown a jacket Susor casing l0 supported by tripod'legs ll. pended within this jacket is a bath vessell3 provided with a flange M at its upper edge adapted to hold-it in position in jacket I0 so that there is anannular space betweenthe'jacket and the ing coi120 allowing for the control of the tem--- perature of afluid in the bath, such as water.

Other heating means Or even cooling means may be. usedxarrd a stirring device, thermostat, or other apparatus may; also be inserted in the bath.

Tube i1; is provided with a restricted orificeiorgallery flange is the lower end of pressure cylinder 26 which is shown in detail in Fig. 2. Below tube l'l'should be located a balance 2t forweighing the sample passing through the tube. This may be any of the Ordinary types of balance and need not be attached to the device.

With'reference to. Fig. 2 there is shown thell to which is' upper portion 0f;sample tube attached gallery flange 25 in which is inserted pressure cylinder 26. It will be noted that the outer wallof the pressure cylinder is beveled so that it is easily removable from the gallery flange and. so that it is easily and effectively sealed when replaced in the gallery flange. The

preferably machined brass.

3 Weights if desirable. The piston 21 should fit in cylinder 26 just tight enough to prevent substantial grease bypassing it but not to create undue friction. For this purpose a clearance of about 0.004 inch is suggested, and the inside diameter of the cylinder should be greater than the diameter of tube IT. The whole device is a precision instrument and should be so constructed. Cylinder 2G is provided with a head 30 adapted to guide piston rod 28 therethrough, and containing an air vent or vents 3| so that air pressure will not retard the downward movement of the a piston. Head 30 is preferably fixed to the cylinder only by friction to permit easy removal in filling the cylinder. For reproducible results the piston rod and cap should be of uniform predetermined weight although any weight differential can be made up by placing weights on top of the cap.

One embodiment of the device adapted to flt a standard Saybolt-Furol viscosimeter comprised a brass or bronze cylinder having a 2 inch diameter, a 1% inch inside diameter and a height of 3 inches. The lower end of the outside of the cylinder was beveled to form a tight joint in the upper end of the Saybolt-Furol viscosimeter gallery flange. The piston rod was of monel metal of inch diameter and inches in length and this was attached to the piston by screw threads. The piston was a brass disc of 4 inch thickness and of a diameter such that it allowed 0.004 inch clearance when fitted into the cylinder. The cap was a brass weight having a hole in the center thereof and only part way therethrough to receive the piston rod and hold it by frictional means.

In the operation of the device water or air is used in the bath and a predetermined temperature attained such as,'77:1 F. The tube I! is filled with the grease sample taking care not to entrap large air bubbles and the temperature of the bath carefully maintained. Cylinder 26 is fitted into the gallery flange and this is filled nearly to the top with an additional amount of the grease sample. The cylinder head 30 and the piston rod and cap are then put in place and a predetermined weight put on top of the cap such as for example a 1000 g. weight. A sheet of paper is placed on the platform of the balance 24 and the weights set for the predetermined weight of sample, such as the weight in grams of 10 cc. of the sample being tested. A dish is then held under tube 11, the cork is removed and a few cos. of the sample allowed to fall in the dish which is then quickly withdrawn allowing the sample to fall on the sheet of paper and at that instant the timer is started. When the balance shows that the desired weight of grease has passed through the tube, the timer is stopped. The dish may be inserted under the tube again while the sample on the paper is removed and a clean sheet of paper inserted and the process repeated. Other methods of operation will be apparent to those skilled in the art.

One method of determining flow characteristics of a grease sample is known as the Convis test and for this test at least five 10 cc. samples of the grease was timed and the average time taken disregarding any result which varies more than 110% from the average of all determinations. The corrected average time in seconds is reported as the result of the Convis test.

Two special chassis lubricants were tested by this method with the following results:

The apparatus is adapted to allow the use of the ordinary Saybolt-Furol viscosimeter, already in use in many laboratories, both as an oil viscosimeter and by the insertion of cylinder 26 as a grease viscosimeter.

The Saybolt viscosimeter is a standard instrument and while it may vary as to heating devices. etc. the tube is of a standard size. There are two orifice sizes and for testing greases the One known as the Saybolt-Furol viscosimeter is most suitable. This is described in A. S. T. M. Standard of Petroleum Products and Lubricants, dated October 1944, page 412.

While the device is adaptable to measuring the pressure-flow characteristics of a wide variety of materials, it is particularly suitable for the control of the consistency of soft greases such as automobile chassis lubricants for the pressure" gun lubrication of automobile spring shackles and similar uses.

tion in determining pressure-flow characteristics particularly of soft greases.

What I claim is:

1. An apparatus for measuring the pressureflow characteristics of greases comprising in combination a Saybolt-Furol viscosimeter and a device adapted to easy removal and insertion into the gallery flange of said viscosimeter comprising a vertical cylinder having its outer surface near the lower end thereof tapered inwardly for a close fit within the gallery flange of said viscosimeter, a piston fitted within said cylinder, a piston rod attached at the upper side of said piston, a cylinder head adapted to guide said piston rod and a cap on the top of said piston rod adapted to hold weights.

2. An apparatus for measuring the pressure- [iow characteristics of greases comprising in combination of Saybolt-Furol viscosimeter and a device adapted to easy removal and insertion into the gallery flange of said viscosimeter comprising overflow flange at the upper end of said tube, and a device adapted to easy removal and insertion" into said overflow flange comprising a vertical cylinder of an inside diameter greater than the inside diameter of said tube and having its outer surface near the lower end thereof tapered inwardly for a close fit within said overflow flange, and a piston fitted within said cylinder adapted to be operated by a weight.

4. An apparatus for measuring the pressureflow characteristics of greases comprising a cone stant temperature bath, a tube adapted to con- 5 tain a sample of grease arranged within said REFERENCES CITED bath nozzle m the lower end of sad t an The following references are of record in the overflow flange at the upper end of said tube, file of this patent. and a device adapted to easy removal and insertion into said overflow flange comprising a ver- 5 UNITED STATES PATENTS tical cylinder of an inside diameter greater than Number N t the inside diameter of said tube and having its 329,237 Parker Aug 21, 190 outer surface near the lower end thereof tapered 1,535,371 Stanley Apt 23, 1925 inwardly for a close fit within said overflow 2,092,223 Payne Sept 7, 1937 flange, a piston fitted within said cylinder, a pis- 10 ton rod attached at the upper side of said pis- FOREIGN PATENTS ton, a cylinder head adapted to guide said piston Number Country Date rod and a cap on the top of said piston rod 577,578 Germany June 1, 1933 adapted to hold weights.

HERSCI-IEL G. SMITH. 15 

